Technologies for producing color hard copy of computer graphics include impact, ink jet, photographic, electrographic, thermal, and pen plotters.
Impact printer/plotters typically use a multicolor ribbon which is struck with hammers in a typewriter-like fashion. A single color is printed for a line or page, the next color is printed for the same line or page, and so on. Major disadvantages of this technology are noise, difficulties in achieving the necessary registration between colors, and a lack of color selection. For example, a printer/plotter using the primary colors of cyan, magenta, and yellow can only produce the additional colors of red, green, blue, and black. No gray scale is possible. Color impact printer/plotters tend to be rather slow (3-5 minutes per print) and have poor resolution.
Ink jet printer/plotters use either a continuous flow of charged droplets, which are electrostatically deflected toward or away from the printing surface, or piezoelectric transducers, which produce a single droplet on demand. Print heads have several nozzles to print in several colors substantially simultaneously. Ink jet printer/plotters that can print in many colors (i.e. each color modulated some number of steps rather than simple on/off) are expensive. Considerable assembly of mechanical parts is required during manufacture. With only intermittent use, the inks may tend to dry out and clog the nozzles.
Photographic systems use panchromatic film to capture images from a cathode ray tube (CRT) or are laser exposed. The former typically use a monochrome CRT with a set of color filters to expose the film. Instant color films are expensive. Conventional laboratory-processed color films are less expensive, but have the inherent processing turnaround time as a disadvantage.
Electrographic systems include those using styli to deposit electrostatic charge patterns on dielectric paper and those using lasers to discharge photoconductors (laser xerography). The charge patterns in either case are subsequently developed with colored toners in sequence. Disadvantages include the necessity of multiple registrations, high failure rate, and high purchase price and maintenance costs.
Thermal printer/plotters heat small areas on a dye-laden sheet, web, or ribbon. The dye is transferred to the receiver as a result of the heat. Because each color is printed serially, either per line or per page, multiple registrations are required.
Pen plotters typically write on plain paper or a transparent material with felt-tip pens. The technology is mature, but the plotters are very slow and colors are limited to the available pens. Filling in large areas of color is extremely time consuming.
Apparatus according to the present invention can be designed to replace the various types of equipment mentioned above, with advantages such as lower cost, faster operation, better registration, and generally improved quality.
The apparatus is extremely low cost because it produces full color prints in a single pass; multiple registration is not required. Each field of primary color information is written independently and simultaneously with a single type of optical beam (e.g. laser diode). Color crosstalk is eliminated by proper orientation of colorant surfaces and propagation direction of the beams.
Typical apparatus according to the present invention for providing patterns of materials, comprises a support member having a plurality of groups of surface areas, with each surface area in a given group facing generally in a predetermined direction that is different from the direction faced by the surface areas in any other group, the surface areas in each group having thereon an energy-modifiable material adjacent thereto, and means for directing energy onto the surface areas in each group in such manner as to substantially modify some of the material without substantially modifying the material adjacent to the surface areas of the other groups.
Typically the material adjacent to the surface areas of one group differs from the material adjacent to the surface areas of another group. Or the same material may be provided adjacent to the surface areas of all groups. Typically the material is substantially evenly distributed adjacent to the surface areas.
The apparatus may comprise also means for positioning a receiver member with a surface thereof adjacent to the groups of surface areas, so as to transfer a substantial proportion either of the modified materials or of the remaining unmodified materials to the receiver surface to form the desired patterns thereon. In some typical embodiments of the invention, the receiver member, at and adjacent to the surface areas, is substantially transparent to the energy, and the energy is directed through the receiver member onto the material. In some other typical embodiments, the support member, at and adjacent to the surface areas, is substantially transparent to the energy, and the energy is directed through the support member onto the material.
Where the apparatus provides patterns requiring treatment to give the desired final patterns, it typically comprises also means for providing the required treatment. For example, apparatus providing a latent image may further comprise means for developing the image. It may comprise also means for fixing the developed image.
In some typical embodiments of the apparatus, the member has two groups of parallel surface areas forming an array of successive (and typically approximately right-angled) grooves, the right sides of the grooves being one group of surface areas, and the left sides of the grooves being the other group of surface areas.
In other typical embodiments, the member has three groups of surface areas approximately perpendicular to each other, forming an array of corners in rows and columns; each corner comprising three contiguous approximately perpendicular surface areas, one from each group, and approximating a corner of a cube; the first corresponding surface areas at the corners being parallel to one another and making up the first group, the second corresponding surface areas at the corners being parallel to one another and making up the second group, and the third corresponding surface areas at the corners being parallel to one another and making up the third group.
In still other typical embodiments, the member has four groups of surface areas forming an array of corners in rows and columns; each corner comprising four contiguous surface areas, one from each group, and approximating the vertex of a square-based pyramid; the first corresponding surface areas at the corners being parallel to one another and making up the first group, the second corresponding surface areas at the corners being parallel to one another and making up the second group, the third corresponding surface areas at the corners being parallel to one another and making up the third group, and the fourth corresponding surface areas at the corners being parallel to one another and making up the fourth group. The surface areas in other useful embodiments of the apparatus may comprise portions of conical, spherical, cylindrical, finned, vaned, or other depressed, protruding, or textured surfaces, regular or irregular; or combinations thereof; in regular or irregular disposition.
Typically the energy is spatially modulated to define the patterns of materials to be provided. The energy may be directed onto all groups simultaneously, or it may be directed onto the groups in sequence.
Each point in the energy pattern may be directed substantially simultaneously onto the surface areas of a group, or the energy may be directed onto the surface areas in beams or sheets that are scanned to cover a substantial part of the groups of surfaces; with each beam or sheet striking an entire surface area (or more) or a part thereof, as determined by the size of the beam or sheet. Typically each beam or sheet of energy scans the surface areas of a different group, and is modulated while it scans the surface areas. The energy directed onto the surface areas may comprise a combination of beams, sheets, and/or patterns. Typically the energy is directed onto the surface areas in each group in a direction predominantly normal thereto; and the energy comprises light or other electromagnetic radiation (as from a laser or a flash tube) that is modulated to define the patterns of materials to be provided. Suitable types of modulation include amplitude modulation and pulse-width modulation.
To form color patterns, the materials typically comprise colorants, dyes, pigments, or precursors thereof. Typically the materials comprise sublimable colorants, and the energy comprises electromagnetic radiation having wavelengths in the absorption bands of the materials, to sublimate the materials. In some typical embodiments of the invention, each material comprises a sublimable colorant in contact with an energy absorbent, and the energy directing means provides radiation of a wavelength in the absorption band of the energy absorbent, to heat it and thus to sublimate the colorant. In other typical embodiments, the material is a colorant in contact with a chemical reagent, and the energy directing means stimulates a chemical reaction that alters the state of the colorant.
In some typical embodiments of the invention, the surface areas of all groups have the same material adjacent thereto; and typically the patterns produced in the modified material are such as to be usable for subsequent modulation of energy. Typically means are included for directing electromagnetic radiation to the patterns, so as to be modulated thereby. Also typically included are means for projecting images responsive to the modulated radiation, and a radiation sensitive member positioned to receive the projected images. The radiation typically comprises light, and the sensitive member typically comprises materials responsive thereto for providing images in a plurality of colors. Some typical apparatus includes means for directing chemical reagents to the patterns, and the patterns modulate the flow of the reagents to form images responsive thereto. Other typical apparatus includes means for providing electric and/or magnetic fields in a region including the patterns, and the patterns modulate the fields to form images responsive thereto.
A typical method according to the present invention for providing patterns of materials, comprises providing a support member having a plurality of groups of surface areas, with each surface area in a given group facing generally in a predetermined direction that is different from the direction faced by the surface areas in any other group, providing an energy-modifiable material adjacent to the surface areas in each group, and directing energy onto the material adjacent to the surface areas in each group in such manner as to substantially modify some of the material without substantially modifying the material adjacent to the surface areas of the other groups. The method may comprise also positioning a receiver member with a surface thereof adjacent to the groups of surface areas, and transferring a substantial proportion either of the modified materials or of the remaining unmodified materials to the receiver surface to form the desired patterns thereon. Or the method may include positioning a receiver member with a surface thereof adjacent to the patterns of modified materials, and directing electromagnetic radiation to the patterns, in such manner as to be modulated thereby.